The long range purpose of this work is to develop the instrumentation and techniques so that the x-ray and other analytical capabilities of the scanning electron microscope can be applied effectively to biological problems. The subjects of present interest are elastin and stratified squamous epithelium. BIBLIOGRAPHIC REFERENCE: Trams, E.G., Lauter, C.J., and Banfield, W.G.: On the activation of plasma membrane ecto-enzymes by treatment with neuraminidase. J. Neurochem. 27: 1035-1042, 1976.